Ninguno

LM117/LM317A/LM317
3-Terminal Adjustable Regulator
General Description
The LM117 series of adjustable 3-terminal positive voltage
regulators is capable of supplying in excess of 1.5A over a
1.2Vto 37V output range. They are exceptionally easy to
use and require only two external resistors to set the output
voltage. Further, both line and load regulation are better
than standard fixedregulators. Also, the LM117 is packaged
in standard transistor packages which are easily mounted
and handled.
In addition to higher performance than fixed regulators, the
LM117 series offers fulloverload protection available only in
IC's. Included on the chip are current limit, thermal overload
protection and safe area protection. All overload protection
circuitry remains fully functionaleven if the adjustment terminal
is disconnected.
Normally, no capacitors are needed unless the device is
situated more than 6 inches from the input filter capacitors
in which case an input bypass isneeded. An optional output
capacitor can be added to improve transient response. The
adjustment terminal can be bypassed to achieve very high
ripple rejection ratios which are difficult to achievewith standard
3-terminal regulators.
Besides replacing fixed regulators, the LM117 is useful in a
wide variety of other applications. Since the regulator is
``floating'' and sees only theinput-to-output differential voltage,
supplies of several hundred volts can be regulated as
long as the maximum input to output differential is not exceeded,
i.e., avoid short-circuiting the output.
Also,it makes an especially simple adjustable switching regulator,
a programmable output regulator, or by connecting a
fixed resistor between the adjustment pin and output, the
LM117 can be used as aprecision current regulator. Supplies
with electronic shutdown can be achieved by clamping
the adjustment terminal to ground which programs the output
to 1.2V where most loads draw little current....